Clamping device for a cutting insert

ABSTRACT

A metal cutting tool assembly comprising a rigid holder blade, an insert receiving slot formed in a leading end of the holder blade and defined between a resiliently displaceable clamping jaw formed integrally with the holder blade and rigid base jaw forming part of the holder blade, spaced apart displacement and supporting surfaces respectively formed in or on the clamping jaw and the holder, and a slot opening key, a pair of spaced apart projecting prongs of the key with adapted to engage the surfaces. At least one of the prongs is displaceable with respect to the holder blade so as resiliently to displace the clamping jaw outwardly with respect to the base jaw into an opening position for insertion or removal of an insert.

This is a continuation of application Ser. No. 08/342,277, filed Nov.18, 1994, now U.S. Pat. No. 5,697,271.

FIELD OF THE INVENTION

This invention relates to metal cutting tool assemblies of the kindwherein an exchangeable cutting insert is releasably retained in aninsert retaining slot formed in a holder blade. The invention relatesparticularly to such a cutting tool assembly wherein the insert isretainably clamped within the retaining slot between a resilientlydisplaceable clamping jaw and a rigid base jaw without the use ofadditional mechanical clamping means such as clamping screws or thelike.

BACKGROUND OF THE INVENTION

One known form of cutting tool assembly of the kind to which theinvention relates involves the so-called “wedge clamping” of the insertin the insert retaining slot. Here, the insert, having a single cuttingedge, is provided with a wedge-shaped body which forcibly inserted andis retained within a correspondingly wedge-shaped retaining slot, theactual clamping of the insert within the slot being effected by theresilient outward displacement of the clamping jaw as a result of theforced insertion of the insert into the slot. With this type of cuttingtool assembly, the resilient displacement of the jaw is effected by theinsertion of the insert into the slot, but when it is desired to removethe insert, special means have to be provided for mechanically ejectingthe insert from the slot, these means involving the direct exertion ofan ejection pressure on the insert. It will be understood that both theinsertion and removal of the insert is accompanied by significantfriction with consequent wear on the blade jaws which are, in general,of a much softer material than that of the insert.

Alternatively, it is known (GB 1379637) to introduce into and clamp aninsert within an insert retaining slot by first of all mechanicallydisplacing outwardly a resiliently clamping jaw, introducing the insertinto the slot and then allowing the jaw to spring back on to the insertin a clamping position. When it is desired to remove the insert from theslot, the clamping jaw is again displaced outwardly, allowing for theremoval of the insert. The outward displacement of the jaw is effectedusing a mechanical key which is displaced in frictional contact with theinside of the clamping jaw, thereby leading to frictional wear of thejaw and/or the key.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new and improvedmetal cutting tool assembly in which the above-referred-to disadvantagesare substantially reduced or overcome.

According to the present invention, there is provided a metal cuttingtool assembly comprising a rigid holder blade;

-   -   an insert receiving slot formed in a leading end of the holder        blade and defined between a resiliently displaceable clamping        jaw formed integrally with said holder blade and rigid base jaw        forming part of the holder blade;    -   spaced apart displacement and supporting surfaces respectively        formed in or on said clamping jaw and said holder; and    -   a slot opening key, a pair of spaced apart projecting prongs of        said key adapted to engage said surfaces, at least one of said        prongs being displaceable with respect to said holder blade so        as resiliently to displace said clamping jaw outwardly with        respect to said base jaw into an opening position for insertion        or removal of an insert.

Preferably, there is formed in the holder blade an extension slotcommunicating with said insert receiving slot and extending rearwardlythereof. There can be formed in the clamping jaw forwardly of saidextension slot a clamping jaw aperture, said displacement surface beingconstituted by a rim of said clamping jaw aperture.

In accordance with one preferred embodiment of the present invention,the supporting surface is formed on an upper surface of said clampingjaw adjacent said extension slot, one of said prongs being adapted toproject into said clamping jaw aperture whilst the other of said prongsbears on said supporting surface, whereby a levering displacement ofsaid one prong with respect to the other prong results in the outwarddisplacement of said clamping jaw.

Alternatively, and in accordance with another preferred embodiment ofthe present invention, the supporting surface is formed in said basejaw, said supporting surface being constituted by a rim of said base jawaperture and wherein said opening key is provided with means fordisplacing said prongs apart whereby, with said prongs projectingrespectively into said clamping jaw and base jaw apertures, displacementapart of said prongs results in said outward displacement of saidclamping jaw.

Thus, with a cutting tool assembly in accordance with the presentinvention, displacement of the clamping jaw, whether effected by alevering action or by way of a direct, linearly directed displacement,is not accompanied by any direct contact, either with the insert or withthe inner surface of the clamping jaw, and in this way damage thereto isavoided or minimized. Furthermore, introduction into and removal of theinsert from the slot is not accompanied by any frictional resistance bythe opposite jaw surfaces and there is therefore avoided frictional wearof these surfaces leading to an extended life of the holder blade as awhole.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and to show how thesame may be put into practice by way of example, reference will now bemade to the accompanying drawings, in which:

FIG. 1 is a side elevation of a holder blade of a cutting tool assemblyin accordance with the present invention;

FIG. 2 is a side elevation showing the retention of a cutting insert inthe holder blade shown in FIG. 1;

FIG. 3 is a perspective view of the cutting tool assembly shown in FIG.2, together with an associated retaining slot opening key;

FIG. 4 is a similar view to that shown in FIG. 3, with a modified formof retaining slot opening key;

FIG. 5 is a side elevation of a further form of holder blade for acutting tool in accordance with the present invention;

FIG. 6 is a perspective view of the holder blade shown in FIG. 5 and acutting insert clampingly retained therein, together with anappropriately mounted retaining slot opening key;

FIG. 7 is a perspective view of a further form of cutting tool assemblyin accordance with the present invention, with an associated retainingslot opening key; and

FIG. 8 is a perspective view of a still further form of cutting toolassembly in accordance with the present invention, with an associatedretaining slot opening key.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As seen in FIG. 1 of the drawings, a holder blade 1 for a metal cuttingtool assembly in accordance with the present invention comprises a rigidbody portion 2 with which are formed integrally a clamping jaw 3 and abase jaw 4. The clamping jaw 3 is coupled to the body portion 2 via arelatively narrow neck portion 5, thereby allowing for a limited degreeof flexible resilience of the clamping jaw 3 with respect to the bodyportion 2 and with respect to the base jaw 4, the latter forming a rigidwhole with the body portion 2.

As can be seen in dotted lines in FIG. 1 of the drawings, the clampingjaw 3, in its unstressed position, has its forward tip 6 directeddownwardly towards the base jaw 4 and is spaced therefrom by a distanceh₁.

In order to allow for the introduction of an insert 7 (shown in FIG. 2of the drawings) having a height h₂, the clamping jaw 3 must bedisplaced upwardly in the direction of the arrow 8 (FIG. 1) so mat itsforward tip 6 is spaced from the base jaw 4 by a distance h₃ whereh₃>h₂. As seen in FIG. 1 of the drawings, there is formed in a leadingend of the holder blade 1, and defined between opposite surfaces of theclamping jaw 3 and base jaw 4, an insert retaining slot 9, a rear end ofwhich communicates with a rearwardly extending extension 10 of the slot9 and a lower, curved aperture 11. As can be seen in FIG. 2 of thedrawings, the location of the extension 10 is such as to be bordered bythe narrow neck portion 5 of the clamping jaw. The lower, curvedaperture 11 is provided so as to ensure that the lower, innermost edgeof the insert is properly located within the aperture 11 withoutencountering the slot wall. The retained insert 7 is abutted by anabutment 12 of the body portion 2, and the upper, innermost edge of theinsert is located within the extension 10. In this way there isprevented possibly damaging abutment of the inner edges of the insertwith the body portion.

As can furthermore be seen in FIG. 2 of the drawings, with the insert 7clampingly retained within the insert retaining slot 9, the clamping jaw3 bears clampingly downwardly on the upper surface of the insert 7 inthe direction of the arrow 13.

There is formed in the clamping jaw 3, forwardly of the neck portion 5,a throughgoing aperture 14, whilst there is formed in the base jaw 4,adjacent a front edge thereof, a throughgoing aperture 15.

Reference will now be made to FIG. 3 of the drawings, for a detaileddescription of an insert retaining slot opening key 21 and the manner inwhich it is used in order to open the insert retaining slot so as toallow for the introduction of the insert. As seen in FIG. 3 of thedrawings, the retaining slot opening key 21 comprises a body 22 having apair of integrally formed legs 23a, 23b from which respectively projecta pair of spaced-apart prongs 24a, 24b.

Located between the legs 23a, 23b and bearing against them is awedge-like spacer 25 having a throughgoing threaded bore 26 throughwhich extends a screw 27, an upper end of which remote from the spacer25 is coupled to a turning handle 28.

Rotation of the turning handle 28 in the direction of the arrow 29results in an inwardly-directed displacement of the spacer 25, therebygiving rise to an outwardly-directed displacement of the legs 23a, 23band a consequent outwardly-directed displacement of the prongs 24a, 24bin the direction of the arrows 30a, 30b.

If now, and prior to the rotation of the handle 28 so as to cause theoutward displacement of the prongs 24a, 24b, the latter are inserted inthe apertures 15, 14 and rotation of the handle 28 takes place in thedirection of the arrow 29, it will be readily seen that there occurs anoutwardly-directed displacement of the clamping jaw 3. As a consequence,the clamping jaw 3 effectively pivots about its narrow neck portion 5,thereby increasing the spacing between the clamping jaw 3 and the basejaw 4 and allowing for the introduction or removal of the insert 7.Rotation of the handle 28 in the opposite direction allows for theclamping jaw 3 to return into a clamped position, thereby clampinglyretaining the insert in position.

FIG. 4 shows a modified form of turning key 33 having a fixed projectingprong 34a and an eccentrically rotatable projecting prong 34b which iscoupled to a turning handle 35, rotation of which in one sense givesrise to widening the spacing between the prongs 34a, 34b and rotation inthe other sense from this widened spacing results in a return to theoriginal spacing.

If now, as before, the prongs 34a, 34b are positioned within theapertures 15, 14, rotation of the handle in one sense gives rise to anoutwardly-directed displacement of the clamping jaw, allowing for theinsertion or removal of the insert.

It will be appreciated that, in the embodiments shown in FIGS. 3 and 4of the drawings, a rim of the aperture 14 in the clamping jaw 3constitutes a clamping jaw displacement surface, whilst a rim of theaperture 15 in the base jaw 4 constitutes a support surface.

Reference will now be made to FIGS. 5 and 6 of the drawings where, ascan be seen, the clamping and base jaws define between them, as before,an insert retaining slot which communicates with a rearwardly-directedextension 10 and a lower, curved aperture 11.

As before, there is formed in the clamping jaw 3 a throughgoing aperture14, but in this embodiment there is not formed any through-goingaperture in the base jaw 4. As seen in FIG. 6 of the drawings, a turningkey 41 is formed with a pair of spaced-apart, fixed cylindrical prongs42, 42b with the prong 42a extending through the aperture 14 whilst theprong 42b rests on an upper fulcrum surface of the holder blade 1. Ifnow the key is rotated in the direction of the arrow 43, it can be seenthat there will be a levering displacement outwardly of the clamping jaw3 with respect to the prong 42b. In this embodiment, the rim of theaperture 14 serves as a displacement surface whilst the holder blade 1,upon which rests the prong 42, serves as a supporting fulcrum surface.

In a modified embodiment shown in FIG. 7 of the drawings, arearwardly-directed extension 10′ of the insert retaining slot 9 isshaped to receive the prong 42b of the key 41, with the other prong 43aextends through the aperture 14. Here again, upon rotation of the key 41in the direction of the arrow, a levering outward displacement of theclamping jaw is effected with respect to the prong 42b. In the case ofthis embodiment, the rim of the aperture 14 again constitutes adisplacing surface whilst the rim of the extension 10′ constitutes asupporting fulcrum surface.

In a still further modification shown in FIG. 8 of the drawings, anadditional aperture is formed in an upper portion of the body portion 2of the holder, adjacent to and spaced from the aperture 14 and displacedinwardly with respect to the slot extension. If now the prongs 42a, 42bare inserted in the apertures 14, 45 and the key is rotated in thedirection of the arrow, levering outward displacement of the clampingjaw is effected about the fulcrum constituted by the prong 42b, with therim of the aperture 14 constituting a displacement surface and the rimof the aperture 45 constituting a supporting fulcrum surface.

Whilst in the embodiments specifically described above clampingretention of a cutting insert having substantially parallel upper andlower surfaces has been described, it will be readily appreciated thatthe present invention can be extended to the so-called “wedge clamping”of inserts having a wedge-shaped body portion arranged to be retainedwithin a corresponding wedge-shaped slot formed in the holder blade.

It will be furthermore understood that the present invention is notrestricted to any particular kind of cutting insert such as, forexample, the cutting insert specifically illustrated, but is readilyapplicable to other forms of cutting inserts.

1. A cutting tool assembly comprising: a) a rigid holder blade, saidrigid holder blade comprising: a body portion, a base jaw integrallyformed with said body portion, a clamping jaw having a leading portion,said clamping jaw being integrally formed with said body portion andbeing resiliently and pivotally displaceable relative to said base jaw,an insert receiving slot having a leading portion and a trailingportion, said slot being defined between said clamping jaw and said basejaw and being adapted to receive an exchangeable cutting insert, adisplacement surface formed in said clamping jaw, said displacementsurface being spaced apart from said insert receiving slot and locatedsubstantially on said clamping jaw leading portion, and a supportingsurface provided on said body portion, said supporting surface beingspaced apart from said displacement surface, the arrangement being suchthat a displacing force applied between the supporting and displacementsurfaces to move said surfaces relative to each other results in aoutwardly directed resilient pivotal displacement of said clamping jawrelative to said base jaw; b) an insert receiving slot opening keyhaving a pair of spaced apart prongs, a first prong of said key adaptedto engage said supporting surface and a second prong of said key adaptedto engage said displacement surface for applying said displacing force;and c) means to force apart said first and second prongs, said meansincluding a wedge-like spacer.
 2. A cutting tool assembly comprising: a)a rigid holder blade, said rigid holder blade comprising: a bodyportion, a base jaw integrally formed with said body portion, a clampingjaw having a leading portion, said clamping jaw being integrally formedwith said body portion and being resiliently and pivotally displaceablerelative to said base jaw, an insert receiving slot having a leadingportion and a trailing portion, said slot being defined between saidclamping jaw and said base jaw and being adapted to receive anexchangeable cutting insert, a displacement surface formed in saidclamping jaw, said displacement surface being spaced apart from saidinsert receiving slot and located substantially on said clamping jawleading portion, and a supporting surface provided on said body portion,said supporting surface being spaced apart from said displacementsurface, the arrangement being such that a displacing force appliedbetween the supporting and displacement surfaces to move said surfacesrelative to each other results in a outwardly directed resilient pivotaldisplacement of said clamping jaw relative to said base jaw; b) aninsert receiving slot opening key having a pair of spaced apart prongs,a first prong of said key adapted to engage said supporting surface anda second prong of said key adapted to engage said displacement surfacefor applying said displacing force; and c) means to force apart saidfirst and second prongs, said means including a fixed prong and aneccentrically rotatable prong.
 3. A substantially rigid holder blade foruse in a cutting tool assembly comprising: a) a body portion; b) a basejaw integrally formed with said body portion; c) a clamping jawintegrally formed with said body portion; d) said jaws being locatedopposite one another and defining therebetween a cutting insertretaining slot within which a cutting insert can be spring clamped; e)slot leading and trailing portions; f) clamping jaw leading and trailingportions respectively and substantially adjacent said slot leading andtrailing portions; g) said clamping jaw being resiliently and pivotallydisplaceable about its trailing portion; h) a displacement surfaceformed substantially on said clamping jaw leading portion and spacedapart from said retaining slot; and i) a supporting surface formed onsaid holder blade spaced apart from said displacement surface; j) thearrangement being such that a displacing force applied between saidsupporting and displacement surfaces to move said surfaces relative toeach other results in outwardly directed resilient pivotal displacementof said clamping jaw with respect to said base jaw for insertion intoand withdrawal from said slot of said cutting insert.
 4. A holder bladeaccording to claim 3 wherein said clamping jaw trailing portion iscoupled to said body portion via a relatively narrow neck portion of areduced height dimension as compared with a height dimension of theclamping jaw leading portion on which said displacement surface isformed, the dimensions being transverse to a longitudinal direction ofsaid clamping jaw.
 5. A holder blade according to claim 4 wherein afirst aperture is formed in said clamping jaw leading portion having anaperture rim constituting said displacement surface.
 6. A holder bladeaccording to claim 5 wherein a second aperture is formed in said holderblade spaced from said first aperture and having an aperture rimconstituting said supporting surface.
 7. A holder blade according toclaim 6 wherein said second aperture is formed in said base jawsubstantially opposite said first aperture.
 8. A holder blade accordingto claim 6 wherein said second aperture is formed substantially adjacentsaid clamping jaw trailing portion.
 9. A holder blade according to claim5 wherein said supporting surface is formed on an edge surface of saidholder blade constituting a continuation of trailing edge surface ofsaid clamping jaw.
 10. A holder blade according to claim 5 wherein saidsupporting surface is formed as a trailing extension of said insertretaining slot.
 11. A cutting tool assembly comprising: a rigid holderblade as claimed in claim 3; and an insert receiving slot opening keyhaving a pair of spaced apart prongs, a first prong of said key adaptedto engage said supporting surface and a second prong of said key adaptedto engage said displacement surface for applying said displacing force.12. The assembly according to claim 11 wherein a rotational movement ofsaid key about said first prong displaces said clamping jaw relative tosaid base jaw.
 13. The assembly according to claim 11 further comprisingmeans for displacing said prongs apart.
 14. The assembly according toclaim 13 wherein said means for displacing said prongs apart includes awedge-like spacer.
 15. The assembly according to claim 13 wherein saidmeans for displacing said prongs apart includes a fixed prong and aneccentrically rotatable prong.